Modern mobile telecommunications standards continue to demand increasingly greater rates of data exchange (data rates). One way to achieve a high data rate in a mobile device is through the use of carrier aggregation. Carrier aggregation allows a single mobile device to aggregate bandwidth across one or more operating bands in the wireless spectrum. The increased bandwidth achieved as a result of the carrier aggregation allows a mobile device to obtain higher data rates than have previously been available.
FIG. 1 shows a table describing a number of operating bands in the wireless spectrum. One or more of the operating bands may be used, for example, in a CDMA, GSM, LTE, or LTE-advanced equipped mobile device. The first column indicates the operating band number for each one of the operating bands. The second and third columns indicate the uplink and downlink frequency bands for each one of the operating bands, respectively. Finally, the fourth column indicates the duplex mode for each one of the operating bands. In non-carrier aggregation configurations, a mobile device will generally communicate using a single portion of the uplink or downlink frequency bands within a single operating band. In carrier aggregation applications, however, a mobile device may aggregate bandwidth across a single operating band or multiple operating bands in order to increase the data rate of the device.
FIG. 2A shows a diagram representing a conventional, non-carrier aggregation configuration for a mobile device. In the conventional configuration, a mobile device communicates using a single portion of the wireless spectrum 10 within a single operating band 12. Under the conventional approach, the data rate of the mobile device is constrained by the limited available bandwidth.
FIGS. 2B through 2D show diagrams representing a variety of carrier aggregation configurations for a mobile device. FIG. 2B shows an example of contiguous, intra-band carrier aggregation, in which the aggregated portions of the wireless spectrum 14A and 14B are located directly adjacent to one another and are in the same operating band 16. FIG. 2C shows an example of non-contiguous intra-band carrier aggregation, in which the aggregated portions of the wireless spectrum 18A and 18B are located within the same operating band 20, but are not directly adjacent to one another. Finally, FIG. 2D shows an example of inter-band carrier aggregation, in which the aggregated potions of the wireless spectrum 22A and 22B are located in different operating bands 24 and 26. A modern mobile device should be capable of supporting each one of the previously described carrier aggregation configurations.
The use of carrier aggregation may pose unique problems for the radio frequency (RF) front end circuitry in a mobile device. For instance, a mobile device using carrier aggregation may require two or more antennas. The use of more than one antenna may complicate the design of the RF front end circuitry, thereby increasing the size and cost of the RF front end circuitry. Additionally, the use of carrier aggregation across certain operating bands may cause undesirable interference between transmit and receive circuitry in a mobile device that renders the mobile device unusable in these operating bands.
FIG. 3 shows conventional RF front end circuitry 28 for use in a mobile terminal. The conventional RF front end circuitry 28 includes an antenna 30, a diplexer 32, low-band switching circuitry 34, mid/high-band switching circuitry 36, low-band transceiver circuitry 38, mid-band transceiver circuitry 40, and high-band transceiver circuitry 42. The diplexer 32 includes a low-band diplexer port 44, a mid/high-band diplexer port 46, and an antenna port 48, which is coupled to the antenna 30. The low-band switching circuitry 34 includes a number of low-band transceiver ports 50 and a low-band output port 52, which is coupled to the low-band diplexer port 44. The mid/high-band switching circuitry 36 includes a number of mid/high-band transceiver ports 54 and a mid/high-band output port 56, which is coupled to the mid/high-band diplexer port 46. The low-band transceiver circuitry 38 is coupled to a first one of the low-band transceiver ports 50. The mid-band transceiver circuitry 40 is coupled to a first one of the mid/high-band transceiver ports 54. Finally, the high-band transceiver circuitry 42 is coupled to a second one of the mid/high-band transceiver ports 54.
The low-band transceiver circuitry 38 includes a low-band receive port 58, a low-band transmit port 60, a low-band power amplifier 62, and a low-band duplexer 64. The low-band receive port 58 is coupled to the low-band switching circuitry 34 via the low-band duplexer 64. Further, the low-band transmit port 60 is coupled to the low-band switching circuitry 34 via the low-band power amplifier 62 and the low-band duplexer 64. The low-band duplexer 64 is configured to separate low-band receive signals about a low-band operating band from low-band transmit signals about the low-band operating band, passing the signals appropriately to either the low-band receive port 58 or from the low-band transmit port 60 via the low-band power amplifier 62.
The mid-band transceiver circuitry 40 includes a mid-band receive port 66, a mid-band transmit port 68, a mid-band power amplifier 70, and a mid-band duplexer 72. The mid-band receive port 66 is coupled to the mid/high-band switching circuitry 36 via the mid-band duplexer 72. Further, the mid-band transmit port 68 is coupled to the mid/high-band switching circuitry 36 via the mid-band power amplifier 70 and the mid-band duplexer 72. The mid-band duplexer 72 is configured to separate mid-band receive signals about a mid-band operating band from mid-band transmit signals about the mid-band operating band, passing the signals appropriately to either the mid-band receive port 66 or from the mid-band transmit port 68 via the mid-band power amplifier 70.
The high-band transceiver circuitry 42 includes a high-band receive port 74, a high-band transmit port 76, a high-band power amplifier 78, and a high-band duplexer 80. The high-band receive port 74 is coupled to the mid/high-band switching circuitry 36 via the high-band duplexer 80. Further, the high-band transmit port 76 is coupled to the mid/high-band switching circuitry 36 via the high-band power amplifier 78 and the high-band duplexer 80. The high-band duplexer 80 is configured to separate high-band receive signals about a high-band operating band from high-band transmit signals about the high-band operating band, passing the signals appropriately to either the high-band receive port 74 or from the high-band transmit port 76 via the high-band power amplifier 78.
In operation, the diplexer 32 passes low-band signals between the antenna 30 and the low-band switching circuitry 34 while attenuating other signals. Further, the diplexer 32 passes mid-band and high-band signals between the antenna 30 and the mid/high-band switching circuitry 36 while attenuating other signals. The low-band switching circuitry 34 selectively routes low-band signals between the low-band output port 52 and the low-band transceiver ports 50. The mid/high-band switching circuitry 36 selectively routes mid-band and high-band signals between the mid/high-band output port 56 and the mid/high-band transceiver ports 54. The low-band transceiver circuitry 38 provides low-band transmit signals about a low-band operating band to the low-band switching circuitry 34 via the low-band power amplifier 62 and receives low-band signals about the low-band operating band from the low-band switching circuitry 34 at the low-band receive port 58. The mid-band transceiver circuitry 40 provides mid-band transmit signals about a mid-band operating band to the mid/high-band switching circuitry 36 via the mid-band power amplifier 70 and receives mid-band signals about the mid-band operating band from the mid/high-band switching circuitry 36 at the mid-band receive port 66. The high-band transceiver circuitry 42 provides high-band transmit signals about a high-band operating band to the mid/high-band switching circuitry 36 via the high-band power amplifier 78 and receives high-band signals about the high-band operating band from the mid/high-band switching circuitry 36 at the high-band receive port 74.
While the conventional RF front end circuitry 28 is capable of inter-band carrier aggregation between the low-band operating band and either the mid-band or the high-band operating band, the conventional RF front end circuitry 28 cannot perform inter-band carrier aggregation between the mid-band operating band and the high-band operating band. Specifically, due to the fact that mid-band signals and high-band signals are not separately filtered by the diplexer 32 and both delivered to the mid/high-band switching circuitry 36, there is no way to separate these signals in the conventional RF front end circuitry 28. Accordingly, the conventional RF front end circuitry 28 may be unacceptable in certain wireless environments in which it is necessary to aggregate bandwidth across the mid-band operating band and the high-band operating band.
Accordingly, FIG. 4 shows the conventional RF front end circuitry 28 further including an additional antenna 82 and high-band switching circuitry 84. In the conventional RF front end circuitry 28 shown in FIG. 4 the mid/high-band switching circuitry 36 is only mid-band switching circuitry 36 such that the mid/high-band transceiver ports 54 and the mid/high-band output port 56 are mid-band transceiver ports 54 and a mid-band output port 56, respectively. Further, the diplexer 32 is configured to route only mid-band signals (rather than both mid-band and high-band signals) between the antenna 30 and the mid-band switching circuitry 36, while attenuating other signals. The high-band switching circuitry 84 includes a number of high-band transceiver ports 86 and a high-band output port 88, which is coupled to the additional antenna 82. The high-band transceiver circuitry 42 is coupled to one of the high-band transceiver ports 86. By adding the additional antenna 82 and the high-band switching circuitry 84 to the conventional RF front end circuitry 28, the conventional RF front end circuitry 28 can operate in inter-band carrier aggregation configurations between the low-band operating band, the mid-band operating band, and the high-band operating band. However, adding the additional antenna 82 consumes additional space in the conventional RF front end circuitry 28 and further adds cost to the circuitry.
FIG. 5 shows the conventional RF front end circuitry 28 as in FIG. 4 wherein the additional antenna 82 is removed and the diplexer 32 is replaced with a triplexer 90. The high-band output port 88 is coupled to the triplexer 90. Further, the triplexer 90 is configured to pass low-band signals between the low-band switching circuitry 34 and the antenna 30 while attenuating other signals, pass mid-band signals between the mid-band switching circuitry 36 and the antenna while attenuating other signals, and pass high-band signals between the high-band switching circuitry 84 and the antenna while attenuating other signals. Accordingly, the conventional RF front end circuitry 28 may operate in inter-band carrier aggregation configurations between the low-band operating band, the mid-band operating band, and the high-band operating band. However, replacing the diplexer 32 with the triplexer 90 results in a significant increase in the complexity of the conventional RF front end circuitry 28. As the filter order of the circuitry increases, so does the complexity, area, and expense associated therewith. Accordingly, constructing a high quality triplexer results in an increase in both area and expense, and further adds insertion loss in the signal path of the antenna 30.
FIG. 6 shows the conventional RF front end circuitry 28 as in FIG. 3 wherein the high-band transceiver circuitry 42 includes a quadplexer 92, an additional mid-band receive port 94, an additional mid-band transmit port 96, and an additional mid-band power amplifier 98 such that the high-band transceiver circuitry 42 is configured to transmit and receive both mid-band and high-band signals. The quadplexer 92 shown in FIG. 6 filters and separates mid-band receive signals about a mid-band operating band, mid-band transmit signals about the mid-band operating band, high-band receive signals about a high-band operating band, and high-band transmit signals about the high-band operating band. In non-carrier aggregation configurations the conventional RF front end circuitry 28 may use the mid-band transceiver circuitry 40 to transmit and receive mid-band signals about the mid-band operating band. However, in one or more carrier aggregation configurations, the conventional RF front end circuitry 28 may use the high-band transceiver circuitry 42 to transmit and receive both signals about the mid-band operating band and the high-band operating band. Accordingly, mid-band and high-band signals are filtered in the high-band transceiver circuitry 42 itself, thereby allowing the conventional RF front end circuitry 28 to operate in inter-band carrier aggregation configurations between the low-band operating band, the mid-band operating band, and the high-band operating band. However, similar to the triplexer 90 discussed above, the quadplexer 92 shown in FIG. 6 is difficult to manufacture, resulting in increases in the area and expense associated with the conventional RF front end circuitry 28. While the insertion loss associated with the quadplexer 92 is limited to a downstream signal path, the performance of the conventional RF front end circuitry 28 will still suffer in a carrier aggregation configuration utilizing the mid-band operating band and the high-band operating band.
Accordingly, there is a need for RF front end circuitry capable of operating in a variety of carrier aggregation configurations using a single antenna feed, while simultaneously avoiding higher order filters such as triplexers and quadplexers.